Been about a week and cannot download 5.71 on M1 Mac Sequoia 15.7.2.
I constantly get MD-DL-200 error in the launcher.
Nowhere does Epic seem to list what this error code means and more importantly how to solve it.
It looks like it is recurring issue but this in the first time it has bitten me as I have been able to download previous versions of 5.#.
Any advice or a solution would be appreciated.
I have the same problem. I live in Turkey and have a Mac mini M2. When I first downloaded the launcher and tried to download UE5.7, it downloaded fine. But then I wanted to download UE4.27 because UE5.7 was lagging. I deleted it and tried downloading 4.27, but I got an MD-DL-200 error after about 2 minutes of initialization. This has been going on for three days now.
(I also tried changing the router settings and using VPN)
I have the same problem. Have you solved it? What is the solution?
Been a long time and several versions of Unreal but I found a fix to let the Launcher download the app. I do not know how legit it is but I am currently downloading 5.8 as I type.
So if you have the same problem I had then try these steps:
On the MAC only:
1/ Close Epic Launcher
2/ Go to Applications folder and select the app
3/ Right Click on it or Control click on it
4/ Select show package contents from the drop-down menu
ALL THESE STEPS HAPPEN WITHIN THE PACKAGE ITSELF:
5/ Open the contents folder
6/ Open UE folder
7/ Open EpicGamesLauncher folder
8/ Open Config folder
9/ Open DefaultEngine.ini file
10/ About 12 lines down is the [HTTP] section
11/ Delete the first line of that section it says: HttpTotalTimeout=##
(This was killing the network precesses and stopping the download.
You can always note what the line says and replace it later.)
12/ Save the changes
13/ Close all folders and reopen the Launcher and cross your fingers. 
As I said it is working for me. You can alway replace the line after you are done.